There is something nicely unexpected about "Dancing on the Edge," writer-director Stephen Poliakoff's seductive drama of jazz and England in the early 1930s.

The series, which begins Saturday on Starz (it has already aired on the BBC), forms a kind of "Upstairs/Backstage" story with a mystery attached and comes in five parts, plus an epilogue — appendix might be the better word — in the form of interviews.

To be sure, jazz has often lurked at the background of British period pieces — Lord Peter Wimsey dragged to some Soho cellar, Bertie Wooster knocking out a chorus of "Minnie the Moocher." The next season of "Downton Abbey" will feature a black American singer (Gary Carr) based on the historical Leslie "Hutch" Hutchinson, who cut a swath through British high society in the 1920s and '30s.

A writer with a long list of fairly high-toned stage plays, film scripts and TV to his credit, Poliakoff was inspired in part by reading of the friendship of Duke Ellington with members of British royalty. In place of Ellington, he gives us Louis Lester (Chiwetel Ejiofor), a rare black British bandleader whose career starts to get traction when he crosses paths with hustling music journalist Stanley Mitchell (Matthew Goode), who is his entree as well to a world of upper-crust jazz fans.

At the suggestion of one (Anthony Head), they acquire a singer — two, in fact (Angel Coulby and Wunmi Mosaku). And things change.

Poliakoff takes his time, with long scenes in which people spend a little time coming to a point. The pace is mostly languorous, despite the jazz theme, and even when the going gets going, steps are only slightly quickened.

Where he falls short, oddly, is the music. The many original songs, all written by Adrian Johnston, sound less like lost classics than not-quite-successful pastiche. Hackneyed lyrics like, "Shout it loud/Head up proud / This girl's going far/Blow, Joe, blow / Let 'em know / I'm gonna be a star" may comment profitably on the action, but they are not Cole Porter or Billy Strayhorn. The music is also — on purpose, it transpires, for effect — too modern for the era, both in arrangement and performance; not everyone will find that jarring, of course, or know the difference.

But Poliakoff is in any case less interested in jazz as music or culture than as a destabilizing, reorganizing force. Notwithstanding a few dropped names, he is scant on context and on the details whose mention and sharing are a natural and important part of that world, for musicians and fans alike. And despite the band's stated rise, there are few scenes that express any palpable connection between players and crowd — or even muster a crowd. But perhaps that's just how it was with the British.

His true business is elsewhere, with the love stories, a murder mystery, the collision of race and class, past and future, of bright hopes and dark desires. He uses the music to gather into close, sometimes very close, quarters a cast of characters whose diverse backgrounds might otherwise keep them apart. Indeed, they tend to go about in a pack as if joined at the hip, and to the exclusion of anyone else.

Rounding out this crowd are John Goodman as an American moneybags who keeps a little gold around (and on display) in case of another crash; a lovely Jacqueline Bisset as a semi-reclusive great lady, compensating for a personal loss by looking into new music; Janet Montgomery as a photographer who clicks with Lester; and Tom Hughes and Joanna Vanderham as one of those neurasthenic brother-sister dyads who promise seven kinds of trouble. The great Allan Corduner plays Stanley's boss, Jenna-Louise Coleman his underappreciated assistant.

The faults are noticeable, really, only because so much else feels right. The film is beautifully shot and apportioned. Its engine hums, in low gear, mostly, but reliably. You are drawn in and along, just as the characters are drawn along, by music or money or sex or love, the taste of something better, hotter, cooler, more rewarding, more alive.